c++ - 错误 : 'ios_base' has not been declared

Question

我正在使用 libcurl 下载序列化代码并将其打开，但是，我收到一个错误，看起来 fstream 丢失了，但它包含在内。我环顾四周，但很少发现错误。下面是错误和代码。错过了什么？

编译错误输出

g++ -g testGetprice2.cpp -o testGetprice2.o -std=gnu++11 -lcurl
testGetprice2.cpp: In function 'int getData()':
testGetprice2.cpp:45:56: error: 'ios_base' has not been declared
testGetprice2.cpp:45:72: error: 'ios_base' has not been declared

代码:

#include "rapidjson/include/rapidjson/document.h"
#include <iostream>
#include <fstream>
#include <stdio.h>
#include <curl/curl.h>
#include <unistd.h>
#include <unordered_map>
#include <string>

using namespace rapidjson;

struct myData
{
        std::fstream *file;
        std::string *str;
};

size_t write_data(void *ptr, size_t size, size_t nmemb, myData *data)
{
        size_t numBytes = size * nmemb;

        if (data->file)
                data->file->write((char*)ptr, numBytes);

        if (data->str)
                *data->str += std::string((char*)ptr, numBytes);

        return numBytes;
}

//function to get coin data and perform analysis
int getData()
{
        int count = 0;

    //begin non terminating loop
        while(true)
        {
                count++;
                CURL *curl = curl_easy_init();
                if (curl)
                {
                        curl_easy_setopt(curl, CURLOPT_URL, "http://pubapi.cryptsy.com/api.php?method=singlemarketdata&marketid=155");

                        std::fstream file("/home/coinz/cryptsy/myfile.txt", ios_base::out | ios_base::ate);
                        std::string json;

                        myData data;
                        data.file = &file;
                        data.str = &json;

                        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, &write_data);
                        curl_easy_setopt(curl, CURLOPT_WRITEDATA, &data);

                        /* Perform the request, res will get the return code */
                        CURLcode res = curl_easy_perform(curl);

                        /* Check for errors */
                        if (res != CURLE_OK)
                        {
                                std::cerr << "curl_easy_perform() failed: " << curl_easy_strerror(res) << std::endl;
                        }
                        else
                        {
                                file << std::endl;

                                //begin deserialization
                                Document document;
                                document.Parse(json.c_str());
                                assert(document.HasMember("lasttradeprice"));
                                assert(document["hello"].IsString());
                                std::cout << "The Last Traded Price is = " << document["lasttradeprice"].GetString() << std::endl;
                        }

                        /* always cleanup */
                        curl_easy_cleanup(curl);
                }

                //timer for URL request.  *ADUJST ME AS DESIRED*
                usleep(10000000);
        }

        return 0;
}

//Le Main
int main(void)
{
    getData();
}

Answer 1

ios_base 位于命名空间 std 中。在 ios_base 之前添加前缀 std::。